Alpha Electret condenser Headphone HPE-888

Many years ago, I purchased an Alpha Electret condenser Headphone HPE-888 with adaptor. As the headphones were not used for many years, I did not realized that the adaptor was missing. Do anybody knows where the adaptor for this headphone model could be purchased? I also would like to know who is or was the manufacturer of this device. There is not indication neither on the box nor in the earphones itself that says where or who made it.

you would have to use another adapter box from something else, another electret, and trace the wiring on the plug end pins to make sure. Only 4 should be needed 2 per side ( haven't seen the things though but this should be right)